Sexual selection in the Orthoptera

Darwin (1871) included numerous examples from the Orthoptera when he introduced the concept of sexual selection. He realised that individuals do not mate indiscriminately but prefer some partners over others. The resulting mate choice is an important evolutionary process that imposes sexual selection on the opposite sex. Darwin also proposed that competition between individuals of one sex for access to individuals of the opposite sex results in selection for traits that enhance the success of the individual in such competition. In species in which females mate with more than one male, we now know that these processes of inter and intra-sexual selection continue after mating, in the form of cryptic female choice and sperm competition. Thus sexual selection is a strong force shaping morphology and behaviour.

The sexes have different investment patterns in reproduction leading to divergent mating interests, which has led to sex-specific traits for the pre-copulatory aspects of mate finding and mate attraction. Basic to mate finding and attraction is some sort of sensory detection, with the sensory organs connecting the environment with the nervous system. Sensory ecology, including the shaping of sensory organs by both sexual and natural selection, is a focus for connecting neurobiology with sexual selection. In the Orthoptera, a group that is renowned for their acoustic communication, there exists a variety of vibration receptor organs, including hearing organs developed from stretch receptors connected to membranes sensitive to airborne vibrations.

The Orthoptera have proved to be excellent model organisms to test Darwin’s concept of sexual selection, and research in this field has flourished over the last few decades. The aim of this symposium is to give an overview of ongoing research in the field of sexual selection in this order, including both pre-and post-copulatory sexual selection and the interactions between sexual selection, acoustic communication, hearing and neurobiology.